1. Technical Field
The present invention relates generally to an acoustical microscopic and, more particularly, to a multieyed acoustical microscopic sensor having a plurality of acoustical transducers.
2. Discussion
Welding is a common process for attaching one metal member to another. This process generally involves heating an interface between the items which are to be welded, thereby melting the interface into one joint or weld nugget. Because this process has its application in many different types of manufacturing, such as automobile manufacturing, inspection ensuring that the weld nugget meets certain quality standards is a must. Specifically, it is desirable to inspect the area, size and configuration of the weld nugget and to determine if any defects exist therein. Uninspected welds may result in weld failure after the welded item is sold or distributed to a final user.
Ideally, a weld is inspected either during or shortly after the welding process so that added inspection does not increase weld time, and to allow weld problems to be identified when they occur. Furthermore, non-destructive testing is preferred so that welded parts which pass inspection may still be sold or distributed to the end user.
Visual inspection systems have been employed in the weld environment for this purpose. Specifically, an individual, such as a quality control person, may gage the size of the weld nugget or destructively test a welded item to determine its internal characteristics. However, these methods have several drawbacks. First, because of the bright light and harsh conditions generated by welding, visual inspection of a weld cannot be performed during the welding process. Instead, the welded item must be inspected off line, adding more time and cost to manufacturing. Second, to properly inspect the weld for defects, the internal structure of the weld nugget must be observed. This, in many instances, requires the welded item to be destructively tested, rendering the welded item useless. Besides the increased cost associated with scrapping an item for the purpose of inspection, it is practically impossible to destructively test all items. As such, destructive testing results in a lower number of samples tested and increased cost to manufacturing.
Acoustical microscopy is one possible solution to this inspection problem. Typically, acoustical microscopes use a single transducer to analyze a test subject or target. The use of such a device to inspect welds has several drawbacks. First, an acoustical microscope employing a single transducer can only inspect one area of the target at any given time. As such, inspection of a complete cross section of a target would require the transducer to be constantly repositioned to ensure that all points on the target are inspected. To obtain a detailed cross section, many readings, resulting in a large consumption of time, would have to be taken. The present invention was developed in light of these drawbacks.